There are many mobile applications that help tired city-dwellers flag down cabs. But Hailo, a London-based cab-app company, is picking up passengers by focusing on giving the drivers a great product. Accel Partners took notice and has given the company a $17 million round of funding.

“In London where competition has been intense, Hailo seems to have emerged by all accounts as the clear leader,” said Adam Valkin, a partner with Accel Partners, in an interview with VentureBeat. “They have done this by … aggregating the largest network of cabs (by far) — 3,000 in just a few months.”

London-based Hailo doesn’t require the cabbie to install any hardware. Instead, it creates two separate, connected mobile applications — one for the driver and one for the customer. The passenger app is fairly standard. It lets a person request a cab, choose a form of payment (cash or credit), counts down until the cab arrives, and asks the passenger to rate the experience. Co-founder and chief executive Jay Bregman, however, believes the driver’s app is the real reason they’re in the money.

“The taxi market is the quintessential mobile app. You’re mobile, they’re mobile,” said Bregman in an interview with VentureBeat. “No one has been able to make big networks of cabs without having the customers. [Drivers are] using this [app] even when there aren’t any customers because the app helps them.”

Bregman says Hailo only fills 20 percent of a driver’s roster in a day, but the other built-in tools attract cabbies to use it even in downtime. This includes the ability to communicate with other Hailo cabbies through the app, create a personal log book to set financial goals each week, and share information about traffic with each other. Indeed, hotel pick-up lines, or places where an accident has been reported, are outfitted with a geo-fence. The app knows when a cabbie has entered that area and is prompted to rate if there is business there.

Hailo isn’t alone, though. Companies like Get Taxi and Uber, the high-end car service app, are entering Hailo’s territory in the U.K. Bregman, however, describes calling Uber a competitor like calling a bus a competitor.

“Uber, by the way, is a fantastic service for the one percent of people who can afford it,” he said. “In San Francisco, Uber works well because the taxi market is so highly dysfunctional.”

Uber, which rents out town cars and offers them to passengers for a markup over the meter price, has boomed in places like San Francisco where hailing a cab on your own is nearly impossible. Hailo makes its money addressing the broader market of cabs already on the road, and takes a transaction fee on credit card purchases.

“I don’t really understand where they fit into the infrastructure in London,” Bergman said of Uber’s move to the rainy city. Investor Valkin stays safe and predicts, “Time will tell.”

Like Uber, Hailo will spend money on Olympics-focused marketing, though Bregman says there’s already a lot of confusion about how the Olympics will work in London this summer. He suspects cabs will leave town instead of braving the traffic. Hailo will mainly use the funding to expand, first to Dublin, Ireland. It will then hire general managers for future international locations and continue growing.

Hailo currently has its app in around 15 percent of the 23,000 available cabs in London. Investors include Accel Partners, Wellington Partners, and Atomico. The app is available on both iOS and Android devices.